How Much Does It Cost to Run a 1500-Watt Heater?
At the US average rate of $0.18/kWh, a 1500-watt heater costs about $0.28 an hour. Below is the full breakdown, and what this size can realistically heat.
Rates and assumptions reviewed · see every source
Cost at the US average rate
These figures assume the heater draws its full 1500W the whole time — true for a heater without a thermostat. With a thermostat, expect 40–70% of these numbers.
| Usage | Per day | Per month | 120-day season |
|---|---|---|---|
| 1 hour a day | $0.28 | $8.25 | $33 |
| 2 hours a day | $0.55 | $17 | $66 |
| 4 hours a day | $1.10 | $33 | $132 |
| 8 hours a day | $2.20 | $66 | $264 |
| 12 hours a day | $3.30 | $99 | $396 |
| 24 hours a day | $6.60 | $198 | $792 |
At $0.18/kWh. Use the calculator above with your own rate — electricity ranges from about 11¢ in Louisiana to over 40¢ in Hawaii.
What a 1500W heater can actually heat
This is the default size, and the one nearly every cost question online is really about. At full draw it is among the most expensive things you can plug into a wall — roughly equivalent to running an electric oven continuously, or twelve modern refrigerators at once.
Realistically: a medium room, roughly 150–200 sq ft, if reasonably insulated. The usual rule of thumb is 10 watts per square foot for a reasonably insulated room, putting this unit at roughly 150 sq ft. Draughts, high ceilings, large windows and genuine cold all reduce that.
Electrical considerations
Draws 12.5 amps — 83% of a standard 15-amp household circuit. That headroom is the entire reason 1500W is the legal ceiling for plug-in heaters sold in the US: anything more would trip breakers in normal use. It also means a 1500W heater effectively owns its circuit. Running one alongside a vacuum, microwave or a second heater on the same breaker will trip it.
Never run a space heater on an extension lead or power strip. Heaters draw sustained high current, and most cords and strips are not rated for it. This is a leading cause of home heating fires. Plug directly into a wall outlet, and keep three feet of clearance from anything flammable.
The verdict
Effective, and expensive when run without a thermostat. A thermostatted model typically cycles at 40–70% duty once the room is warm, which is by far the largest lever on the figures below — larger than any difference between heater brands or types.
The comparison that matters
Every electric resistance heater is exactly 100% efficient — all the electricity becomes heat. That sounds ideal until you compare fuels. Electricity delivers heat at roughly $0.18 per kWh of warmth; natural gas through a 95% furnace delivers the same warmth for about 5.6¢. Electric heat costs around three times more per unit of heat.
So a space heater saves money only when it lets you heat less — one room warm with the central thermostat turned down. Run alongside unchanged central heating, it is pure added cost.
Related
- Full space heater calculator — any wattage, with fuel comparison
- Compare all heating fuels
- Estimate your whole bill
Common questions
How much does it cost to run a 1500 watt heater for 8 hours?
About $2.20 at the US average rate of $0.18/kWh. Over a 30-day month at 8 hours a day that comes to roughly $66. Your own rate matters more than any other input — electricity ranges from about 11¢/kWh in Louisiana to over 40¢ in Hawaii, so check your bill and use the calculator above.
How much does it cost to run a 1500 watt heater 24/7?
Around $6.60 a day, or about $198 a month, if it truly runs continuously at full power. In practice a heater with a thermostat cycles off once the room is warm, typically running 40–70% of the time, so the real figure is often closer to half that. A heater without a thermostat genuinely does draw full power the entire time.
Is a 1500W heater cheaper than central heating?
Only if it lets you heat less. Electric resistance heat costs roughly three times more per unit of heat than natural gas. So running this heater instead of heating the whole house — one room warm, thermostat down — can save money. Running it alongside unchanged central heating simply adds cost.
What size room will a 1500W heater heat?
Roughly a medium room, roughly 150–200 sq ft, if reasonably insulated. The common rule of thumb is about 10 watts per square foot for a reasonably insulated room with average ceilings, which puts this unit at approximately 150 sq ft. Draughty rooms, high ceilings, large windows and cold climates all push that number down.